The present invention relates broadly to processes for the removal of trace quantities of hydrocarbon compounds from industrial waste water. More particularly, the present invention relates to a batch process for the treatment of waste water to remove trace quantities of hydrocarbon compounds such as halogenated hydrocarbons which are considered toxic or carcinogenic, and to decompose or convert such compounds to less noxious waste compounds. Moreover, the present invention relates to a process wherein an adsorbent is rendered free of organic matter and made water-soluble after it has lost its adsorptive ability.
As will be recognized by those skilled in the art, various processes of utilizing an adsorbent to remove hydrocarbon compounds from waste waters are known. Adsorbents suitable for such processes include silica gel, activated carbon, clays and activated alumina. However, one of the major concerns associated with the use of an inorganic adsorbent to remove hydrocarbon compounds which are considered toxic or carcinogenic is disposal of the adsorbent after it has lost its adsorptive ability. The solid remnants are considered a contaminated solid waste, and hence proper disposal in a difficult endeavor.
One related prior art waste water treatment method is disclosed by Oleson, U.S. Pat. No. 4,076,615, issued Feb. 28, 1978. The latter system treats waste water with an acidified carbon/alumina mixture followed by filtration of toxic solids and the aeration with an oxygenated gas stream. Although the '615 system may ultimately reduce the hydrocarbon compound content in waste water, no suggestion is provided therein as to the desirability of converting the solid waste products obtained from filtration into non-toxic, readily disposable, or marketable compounds. Oleson alternatively suggests treating the activated carbon/alumina product with sulfuric acid as a means of obtaining aluminum sulfate or alum, but teaches no efficient method of doing so. Moreover, the system suggested by Oleson requires multiple recycles, which can be expensive, cumbersome, and rather inefficient.
The more recent U.S. Pat. No. 4,661,256 issued to Johnson on Apr. 28, 1987 discloses a method for removing halogenated hydrocarbon compounds from waste water and subsequently hydrogenating the solutions with carrier materials such as alumina or silica and a selective metallic component. The Johnson system broadly suggests the need for neutralizing the recovered waste products and lists several possible adsorbents. The contaminated waste water is first channeled into a pressurized adsorption zone. The adsorbent is then regenerated employing an elution solvent in liquid or gas phase. The resulting product of regeneration is introduced into a hydrogenation zone for specified periods required to effectuate reduction of hydrocarbonaceous materials, and subsequently scrubbed with a basic scrubbing solution such as calcium hydroxide. The spent scrubbing solution must be neutralized before disposal, and it is suggested to recycle the recovered hydrocarbonaceous phase for cleansing in accordance with the disclosed system.
There is a steadily increasing demand for technology which not only eliminates trace quantities of hydrocarbon compounds from industrial waste waters, but which also eliminates and decomposes or converts them to non-hazardous compounds suitable for proper disposal. There is also a great demand for technology which is capable of destroying or decomposing the concentrated hydrocarbon waste materials which are separated from a water phase by other extractive methods, without releasing toxic gases or aqueous materials into the environment.